A hurricane releases the bulk of its energy through cloud and rain formation. An average storm's daily cloud and rain energy output is equal to 200 times of the world's electricity-generating capacity.
New Orleans was founded in 1718 by the French. Since that time the Crescent City has weathered many storms, but its geographic position has become increasingly precarious. Miles of storm-protecting wetlands have eroded, effectively moving the city closer to the Gulf of Mexico. The city is gradually sinking lower below sea level and becoming more dependent on its extensive levee system to keep water out.
The levees that protect the city from river flooding are actually a culprit in wetland loss. They deprive the delta of periodic floods, which replenish silt and fresh water.
Previous storms have shaped the size and extent of the New Orleans levee system. In September 1947 an unnamed hurricane flooded metropolitan New Orleans to depths of about three feet (one meter). After the storm, hurricane protection levees were built along Lake Pontchartrain's south shore.
Hurricane Betsy made landfall some 50 miles (80 kilometers) east of New Orleans on September 10, 1965. Winds in the city reached 125 miles an hour (200 kilometers an hour), and the storm surge neared ten feet (three meters). After extensive flooding, the Orleans Levee Board raised existing levees to a height of 12 feet (4 meters).
The most expensive hurricane to make landfall in the U.S. was Hurricane Andrew in 1992, which caused some 25 billion dollars (U.S.) worth of damage in the Bahamas, Florida, and Louisiana. Katrina's economic costs are unknown for now but are sure to be staggering. Risk Management Solutions, a company that assesses the financial impact of natural disasters, estimated on September 2 that Katrina could drain some 100 billion dollars (U.S.) from the economy. That figure would make Katrina the costliest storm in U.S. history.
NOAA has predicted a 95 to 100 percent chance that the 2005 Atlantic hurricane season will be more active than usual. National Hurricane Center forecasters warn that the bulk of 2005's storms are likely still to come.
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